Gun Review: ZRODelta Modulus 9mm Modular Pistol System

They tell me the ZRODelta Modulus is one firearm, but it sure feels like three. Scratch that, nine. More? The maths are hard to suss out, but with this complete Deployment Kit the configuration options are deep and wide.

So that’s it. That’s the actual gun. At least, the part our benevolent government overlords have deemed the “firearm” that must be serialized and otherwise marked. Then you add the other parts, which are available a la carte or all at once in the Baller Kit. Err, Deployment Kit:

Click photo to view full-size.

Holy crap. This is a lot of stuff. Let’s see, there are three slides (all cut for an optic and all with a blanking plate), barrels, and recoil spring assemblies. Three Picatinny rail dust covers, three backstraps, two frontstraps, three magazine wells, two magazines, and the grip module.

Oh! And all of the tools you’ll need to swap all of those parts around. And some spare hardware to replace the screws you drop through the floor register.

I know what you’re thinking. No, the USB flash drive doesn’t plug into the Modulus anywhere. Unfortunately. (please direct all Big Brother-related feedback to Dan). It contains the owner’s manual and…well…heck if I know, who reads owner’s manuals?

Thankfully, it’s all pretty darn self-explanatory.

With one hex wrench and one Torx wrench, the user can swap between all three magazine wells, all of the front- and backstraps, and all three accessory rails and, therefore, all three slide lengths. Quickly and easily.

The short-and-skinny magwell seen above provides a carry-sized grip height, but in 20 seconds . . .

You can move over to a full-length grip with a massively-flared, competition-style magwell.

Every part of the ZRODelta Modulus (or MOD•U•LUS per the logo) is extremely precisely machined. The magazine wells even snap into place via the tab visible at rear just in front of the bolt hole. Slide the magwell into place and then press and CLICK, the tab snaps over a corresponding rib inside of the grip frame, holding everything in place as you insert and snug the retaining screw. Nice.

At about twice the width of the magazine, this funnel is hard to miss.

Each magazine well serves a different use and changes the height and feel of the Modulus. For instance, while retaining the extended length slide . . .

The flared magwell completes the competition look, feel, and function.

The short magwell makes for a drastic change. Clearly much more than just flare diameter, the magwells really make a difference in grip height. With the shorty module on, the Modulus is G19-ish compact in size and ready for concealed carry.

The medium magwell is, then, somewhere in the middle. It’s basically a full-size (G17-ish) height, but without the skirt of the flared magwell unit.

Though, as you can see above, the medium magwell does provide more of a funnel than the shorty option. It’s wild how much of a difference these make with one bolt and 20 seconds.

This has much to do with the design of the grip module, which is kept short and slim in order to let the magazine wells, front- and backstraps, and accessory rails have a big effect on the end product. That is, the specific Modulus configuration created by the owner.

Frontstraps, whether flat or finger-grooved, are machined with what is effectively a T-slot and they slide up a matching rail on the grip module. They’re then held in place by the magazine well of your choice.

Backstraps are a similar story, though a little more involved. They slide into grooves at the rear of the serialized chassis and then a cross pin is pushed through.

This can be done by hand or with any of the tools, as it slides in easily. Then, when the magazine well bolt is tightened (it actually threads into the backstrap rather than into the grip module) everything is thoroughly snugged up and that cross pin isn’t going anywhere.

Inside the backstraps was the only place in any component of the Deployment Kit where I found unsightly machine marks (up at the inside top they all have some aggressive step and tool path marks). In fact, machining quality overall is incredible. Truly top notch.

And the fit between all of the components is fairly incredible as well. While, close up, the gun may look like it might not feel…contiguous?…like one solid unit?…like it’s full of seams and gaps and maybe that it would wiggle or shift a little?…this is absolutely, 100 percent not the case.

Those lines look like lines but they don’t feel like them. If the Modulus were machined from a single chunk of aluminum, it would feel no different in the hand. Including while shooting; it’s rock solid.

Unfortunately, because the fit is so dang precise and the machining so darn good, I’m not confident that much of the aftermarket will be able to whip up bolt-on components of its own that work as seamlessly and solidly on the Modulus as the factory parts. And obviously it would be very cool if a bunch of companies jumped onto it and started offering their own pieces for this MOD•U•LUS puzzle.

Like frontstraps, including in different colors and materials. Right? Limitless opportunities here to bolt cool stuff to this chassis, whether it’s parts that fit on the existing grip module or literally creating an entirely new gun — doesn’t even have to remain a pistol — that starts with nothing more than the serialized chassis.

After shooting with both, I preferred the frontstrap with the finger grooves. Though usually I view finger grooves as a risk for the gun manufacturer since they won’t work with all hand sizes, the ZRODelta Modulus’ grooves worked perfectly for me and, if they hadn’t, it’s an extremely fast and easy swap over to the flat flavor.

I shot the Modulus in its Compact format. It shot great.

I shot the Modulus in its Duty format. It shot great.

I shot the Modulus in its Extended format with a U.S. Optics red dot mounted up. It shot great.

I even configured the Modulus with Extended slide on Compact frame and vice versa, straight-ish backstrap (my favorite — it changes the effective grip angle to make it less swept and closer to 1911 than GLOCK), extended beavertail backstrap, both frontstraps, all magwells, etc etc. It all shot great.

And it was a lot of fun. There was coffee and hanging out at The Range at Austin and lots of Armscor ammo (and other ammo) turned into noise and holes in paper.

Overall I think it’s fair to say that the Modulus 9mm shoots more or less like a well-tuned GLOCK, but feels better in the hand. Partially that’s due to better ergos and partially to the stout, strong feel of a metal frame, plus nice touches like the aggressively undercut trigger guard and high beavertail.

But the timing of it and the geometry of the locking system, the trigger, the general shape, and more are all essence of GLOCK. Which is no surprise, really, as the Modulus 9mm is Gen3 GLOCK components compatible. Not everything, of course, but triggers, slides, barrels, sights, magazines, extractors, firing pins, takedown levers, and more are all Gen3 GLOCK footprint.

Chris’ tender hands found the vertical serrations on the backstrap — specifically, the outermost one on each side — too sharp. They rubbed him the wrong way. If I twist my grip I can absolutely see exactly what he’s talking about, but it didn’t bother me while shooting like it did him.

The Modulus feels familiar in the hand for a GLOCK shooter, but at the same time better, curvier, more ergonomic, and more substantial. Not in weight, but in feel or texture. That aluminum versus plastic thing.

From U.S. Optics’ much more affordable, overseas-manufactured line dubbed USO, comes the DRS (Dynamic Reflex Sight) seen above.

I haven’t tested it in enough scenarios or knocked it around enough to review it, but it was a solid performer at the range. The dot was clean and precise at the lower brightness settings appropriate for the indoor lighting and then grew a bit in size and edge fuzziness as it went up to quite-impressively-bright-indeed levels.

I didn’t bother sighting in the DRS (so don’t mind the off-center groups), but that nice red dot still came in handy for showing that the Modulus is a straight shooter at 25 yards. It won’t set records or anything, but for a GLOCK-compatible design shooting inexpensive ammo it’s a solid performer.

Without a doubt I put up better groups at 25 yards with a red dot than with iron sights. My eyesight ain’t what it used to be (in fact, I usually shoot test groups with my stronger, not-badly-in-need-of-vision-correction, non-dominant eye).

And, while I absolutely love an all-black, serrated rear sight like what’s included on the Modulus, I need something happening up front to help me out. A white dot, a brass bead, a fiber optic, whatever. The black-on-black thing is acceptable for slow, precision stuff but it slows me down for everything else.

Though the ZRODelta Modulus is compatible with Gen3 GLOCK components, it clearly is not a GLOCK. Nor is it made with what are generally considered to be GLOCK’s somewhat loose clearances.

Dropping in an aftermarket threaded barrel, it fit great but also ever so slightly more snugly than in a GLOCK brand GLOCK slide. I could just barely feel it in the lockup, popping into place with the slightest of snicks rather than just plopping in there all plenty-of-room-to-spare like.

The on-the-range result of this was that it ran flawlessly with nothing on the muzzle regardless of ammo choice, ran flawlessly with a suppressor when shooting full-power ammo (e.g. 147 grain HST, defense-loaded 115 grain hollow points, and 124 grain NATO-spec stuff), and ejected very weakly and sometimes not completely with a suppressor while shooting range-power, subsonic ammo.

It was close enough that I think with some lube on the barrel hood and some break-in it would become reliable in that third scenario, too. But for me, on the outing I shot the Modulus suppressed, it wasn’t reliable with range fodder subs.

So what do you think? Is this nuts or what? How many possible configurations can you count? I mean, someone [else] should legitimately do the math, right?

I suppose as the big config changes go, there are three slide lengths and three frame options, all of which can be mix-matched as you please. So…nine different, optics-ready guns? When I put it that way, the Deployment Kit’s $2,799 seems like a screaming deal.

Put another way, it’s more than a GLOCK. But in a land where a ZEV or an Agency Arms “Gucci GLOCK” can run up to $2,000, the cost of this gigantic ZRODelta kit isn’t at all out of bounds. And it’s a great shooting pistol in every configuration.

Of course, if you don’t envision taking full advantage of the Modulus’ extreme modularity, ZRODelta sells full Moduluses in each of the three primary configurations: Compact, Duty, and Extended. Decidedly less cool than this entire kit, but still a very sweet gun with the option to add component parts later.

While I’m not sure I could bring myself to swing for the Deployment Kit, I could see purchasing a Duty pistol plus the Compact magazine well a la carte. The other stuff is cool, but would I really put it to use? Perhaps I’m not baller enough, though if I were I’d for sure display the Modulus Deployment Kit in its case (see lead photo) under glass in a nice frame and hang it on my wall.

Specifications: ZRODelta Modulus 9mm

Caliber: 9×19
Capacity: 17+1
Barrel Lengths: 4-inch, 4.5-inch, and 5.25-inch
Slide Lengths: 6.75-inch, 7.5-inch, and 8-inch
Trigger: 5.5 lbs
Weight: 23.5 ounces to 27.3 ounces (complete Compact to complete Extended)
MSRP: $2,799 for complete Deployment Kit. $1,299, $1,349, and $1,400 for Compact, Duty, and Extended pistols, respectively.

RATINGS (out of five stars):

Style and Appearance  * * * * *
Dude, I like it. Every configuration of it. And the cuts in the extended length slide look great.

Ergonomics  * * * *
Hey I’ve had better, but it sure one-ups a GLOCK.

Customization  * * * * *
Um, yeah, the Modulus sets the new bar for what five stars in this category means. Not only does it do the Erector Set on steroids thing it does, but it’s compatible with one of the most prevalent aftermarket gun parts segments in the country: Gen3 GLOCK parts.

Accuracy  * * * 
Didn’t delight or disappoint.

Overall  * * * *
The ZRODelta Modulus is definitely rad and probably groundbreaking. It’s an incredible feat of engineering with machining, fit, and finish quality through the roof. I even think it’s priced pretty freakin’ well for what it is. But I can’t quite bring myself to give it five stars — we’ll call it a very strong four, though. At least for the Deployment Kit. If I’m honest I just don’t envision users taking advantage of the modularity. We like to think we will, and then we find our favorite configuration and everything else collects dust. In the Modulus I could see running the Duty-length slide all the time and swapping between the Compact and Duty magazine wells. But that’s it. $1,365 and I’m there. The rest is just baller status. Not that there’s anything wrong with that. Now, if the aftermarket jumps in and all sorts of crazy bolt-ons become available for the Modulus chassis, I may have to go back to the calculator and add that fifth star. Could be the hot new ticket.


  1. avatar Scott says:

    This is perfect if your wife says you can only buy one handgun.

  2. avatar billy-bob says:

    It’s cool. But is it 4 AR’s and a case of ammo cool?

    1. avatar James Campbell says:

      To answer your question, YES.
      The four AR (even without the case of ammo) purchased for $1350 will be VERY standard fare, bordering on ho-hum. ARs just start to enter the “cool” factor at around $1500 EACH, unless you’re running with gamers who are new to “real” ARs.

      1. avatar James Campbell says:

        EDIT; My bad, just saw the total price for the entire package, no it’s not a cool handgun at that price.


    “Oh! And all of the tools you’ll need to swap all of those parts around.”

    Whia tools! They are *excellent* quality tools of proper German heritage for working on small things…

    1. avatar strych9 says:

      Or… perhaps on die klienvolk?

      1. avatar Sam I Am says:

        “Or… perhaps on die klienvolk?”

        Or Untermensch?

        1. avatar strych9 says:

          I was thinking more like “pleb” but… I guess it’s kind of synonymous with subhuman to those who think that way.

  4. avatar Specialist38 says:

    Kind of like a Glock designed by someone who actually shoots gun.

    Too pricey for me but it cool to see what can be done with modern design and manufacturing technology.

    Great to see a Jeremy review. Always informative and entertaining.

  5. avatar TommyGNR says:

    I can build 3 Glocks to my personal specs for that money.

    1. avatar Ben says:

      My thoughts exactly. I mean I can get a gen3 or gen 4 19, 17 and 34 for about $1,500 and upgrade them to the max and still spend less. Oh and I don’t have to swap stuff around before I go shoot.

    2. avatar Dyspeptic Gunsmith says:

      Yes, you can.

      But in places where you’re very tightly limited in how many handguns you can own, this technology is akin to the drilling or the rifle with quick-change barrels and bolts. One serial number, lots of different guns.

      I applaud developments like this, because this is a response to more gun control foolishness, showing yet again, that gun people will get around whatever regulation or legislation is put in their way. Gun banners are just too consumed with their moral preening to realize how ignorant they really are…

  6. avatar guest says:

    9 different guns! It’s actually just one.

  7. avatar Sam I Am says:

    Close, but no seegar. Wake me when the kit supports .22, .357 .40 caliber.

  8. avatar MouseGun says:

    So, it’s a non-Glock Glock that does Glock things and takes Glock mags and Glock parts? Is this what the pinnacle of industry stagnation looks like?

  9. avatar Gadsden Flag says:

    The new Dan Wesson for a new millennium. Begs the same question. Why?


      “The new Dan Wesson for a new millennium.”

      You can thread in a new barrel?

    2. avatar Specialist38 says:

      Because they can!

      May not be practical, but somebody will think its cool……and buy it.

      Had a friend in college with an HK P4 with barrels in 25, 32, and 380.

      He never shot anything but 380 through it……but he could have if he wanted.

      People like gadgets and doo-dads.

      Everyone I know that has bought a 300 AAC set up for their AR ends up making a dedicated gun out it. They just tired of switching it around.

  10. avatar Latemarch says:

    Don’t forget the price of holsters for all those combinations.

    1. avatar Hannibal says:

      If you can find them…

      1. avatar SoCalJack says:

        For many kydex holsters the passive retention is at the front of the trigger guard if no WML. So you could have one holster with an open bottom for differnt slide lengths and it’ll have a cut for an optic. Assuming these kits sell, the first company to make a IWB/OWB modular holster wins…that’s my guess.

    2. avatar CarlosT says:

      Get a holster without a bottom, like a Yaqui slide. It’ll fit regardless of barrel length.

      1. avatar Gadsden Flag says:

        Carlos, I’ve had a Yaqii slide since the ’80s. That’s not the issue. The issue is if I want a different handgun I’m not going to build it. I’m going to pick it up and walk out the door.

  11. avatar No one of consequence says:

    Kinda sorta been doing this with Polymer80 frames and slides….

    Granted not as nice of a finish; but I can do it with multiple calibers too.

    1. avatar Jeremy S. says:

      While ZRODelta doesn’t offer other calibers, you could still do that on your own here. All that stuff is available for Gen3 Glock so you could swap to .22 LR, .22 TCM, .357 SIG, .40 S&W, .45 GAP, and probably others I’m forgetting are out there. Toss your OEM G22 slide on top of the Modulus, etc etc.

  12. avatar RA-15 says:

    I like it , metal frame is very cool , I’d loose the gen 3 ejector and mim extractor first off . That’s if I could afford it. It does have the cool factor. I dont think anyone would argue that. Nice review Jeremy , thanks.

  13. avatar Hannibal says:

    Modular guns certainly have applications but I have to wonder if your average civilian gun owner (who doesn’t have to worry about having armorers and logistics for different combat roles) will really use them for much more than the cool factor. Sure, you can take this gun and switch it around between compact, duty, etc sizes- but for the MSRP you could just get several guns instead and not have to fiddle with them every time you want to change things up for a different type of carry that day. Glock is the obvious (and boring) answer to that question, but there are other guns that have different sizes but function the same.

    It could also theoretically be useful in circumstances where, for some reason, you can only own one gun. Restrictive states where it’s a pain to buy a handgun come to mind… however, those same states are going to have a problem with the capacity.

    I dunno. Modular concepts seem to be the new prize pig in town along with high capacity subcompacts but it just feels like it’s a result of stagnation in the small arms area. I guess someone will buy it.

    1. avatar Hannibal says:

      (and it doesn’t even have different caliber options at that price?)

    2. avatar pwrserge says:

      Some states… [cough]NewYork[cough] require a separate permitting process for each handgun you own. Seems like an easy way to save yourself a pile of paperwork. Some people have jobs that prevent them from moving out of commie dominated states.

      1. avatar Jerms says:

        Man, you and alleged communists…

        1. avatar pwrserge says:

          Have you paid attention to the DNC platform lately?
          “Green New Deal” including “economic security” for people unwilling to work.
          “Medicare for All”
          Abolishing private health insurance

          There’s nothing “alleged” about it these days.


          “Man, you and alleged communists…”

          He’s more qualified than you are as to who is and who isn’t commie scum, since he grew up under Soviet rule…

        3. avatar pwrserge says:

          … also have a wonderful document from the Soviet government posthumously “exonerating” a member of my family 30 years after the NKVD dragged him out of his home in the middle of the night, put a bullet in his head, and dumped his body in an unmarked mass grave. Then left his widow and son to nearly starve to death on their own farm because they decided all the produce from that farm had to be “redistributed” for “the common good”.

          That’s one horror story from one branch of my family. I’ve got a half dozen others. (Though they don’t come with a sanctimonious “sorry we shot your family member” note from the government.)

        4. avatar Dyspeptic Gunsmith says:

          As of this election cycle, there is no longer any “alleged” about it. The DNC has gone full socialist, and to quote a guy who was something of an expert on the topic (ie, he knew more than you do on the issue of socialism), “The goal of socialism is communism.”

          I hear they’re still keeping the corpse of the author of that quote around at a cost of about $250K/year in Moscow.

      2. avatar Hannibal says:

        Yeah but again this would be a no-go in NY or any other such states due to the capacity over 10.

    3. avatar Sam I Am says:

      Thinking if I buy three (or more) single-purpose guns, that means three (or more) guns to clean. With changeable barrels and springs, only one gun, and extra barrel to change. Of course, the kit would lead to cleaning three guns.

  14. avatar strych9 says:

    Kinda cool but it seems impractical to me.

    For the price of three (or more) guns you could have one super modular gun or… three guns. If you’ve got three guns and don’t like two of them you can sell two and still have one. Life takes a turn and you need to divest, same thing.

    With this you’re “sell one” and you’ve sold all three and now you’re trying to sell something pretty specialized for a high price which limits your resale potential.

    Personally if I’m going to drop $3K on pistols at the gun store I’d rather get three guns or one gun I really, really want… which isn’t gonna be a gun that tries to be two other guns.

    Besides, if you even talk about this thing in Canada you’ll end up in jail if you mis-pronoun it because it’s an extended slide that identifies as a compact.

  15. avatar Hal_Greaves says:

    one can buy 3 glocks and a shadow 2 for $2700 if they look around enough

    1. avatar billy-bob says:

      Or 18 Hi Points.

  16. avatar GS650G says:

    I’m sure a rich liberal will buy one. Or two.

  17. avatar jbob says:

    More shit to break and make it unreliable.

  18. avatar Sam Hill says:

    Dealing in druthers , I’d druther have one completely tricked out 1911 or a nice rock island fs .45 and 2 baby rocks in. 380. And as always anything having to do with glock sounds like something nasty hitting the wall.

  19. avatar FB says:

    Very niche market.

  20. avatar BusyBeef says:

    Every day we stray further from God’s light.

    1. avatar Happy Heathen says:

      Not me. I run as far away as I can, as fast as I can.

  21. avatar Will Drider says:

    No thanks. This could also be one broke gun turns into three. We have the similar issue buying additional uppers (caliber, barrel length/type, optics base): you can’t give 1/2 or 1/3 of a gun to someone so they can cover you Six. Doesn’t work no matter how you slice it or how many configurations you can build. In my limited history, the Dan Wesson Pistol Pack was one revolver frame and multiple barrels plus additional barrel options from DW Retailers. Cool but after folks did the quick chane a few times, these guns normally stayed in one configuration. They are worth more now because: low marked demand = low production numbers. I don’t believe a person will change it from Compact (CC use) to Full (House gun) then prior to a shooting match change it to Extended.

    Yes, you can buy it in a single configuration BUT your still paying to offset a “modular receiver” you don’t need and larger development/engineering costs that your version fell out from. I don’t choke up on gun prices but think about buying a singular “compact” with a price point of $1300 and ask your self: What would draw you to it if your not going to play the erector set game? Nada.

  22. avatar Scott H says:

    I am glad I live in a free state! I like the idea of three actual pistols rather than only one gun that can be made up into 9/12 different guns.

    For the price you could build 3 different size P80 pistols (all P80 parts aside from a 34 slide and barrel that you buy elsewhere) and have plenty of coin left over. You could buy a Gen 5 17, 19 and 34 for a lot less.

    The ability to construct different grips is really cool though… probably the next thing in “Gucci Glocks.”

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